Low Voltage Warnings

[lyncha00]

Looking for some help with a charging issue. 2009 Tournament 275 with single F350 and two battery switch set up. Both batteries have been load tested and check out. I only use 1 battery at a time (ie go out on battery 1, come back on battery 2, etc).

At idle speed no issues at all, seeing 14.1 volts on both Yamaha gauge and meter on batteries directly. After 15 minutes on plane, voltage drops to under 12 volts and starts flashing. Same thing happens on either battery. Have checked/cleaned all connections at batteries and battery switch (they didn't look terrible to start with). Don't know where it is grounded to or how to check that. Thinking weak alternator output on engine? Appreciate any thoughts.

 

[seasick]

Do you have a shore powered charger? I am assuming no since the voltage wouldn't be 14+ at first if the batteries had been topped off. The only thing that comes to mind id a bad charging system component like you suspected that goes bad when it gets warm. I believe there is a fuse also for the charging lead of of the motor. I would check that area also.
What happens after you get the alarm, shut down, wait 20 seconds or so and then restart? Does it crank OK and what voltage do you read?

 

[lyncha00]

I can shut motor off and restart no issues, cranks fine but it's immediately flashing low voltage.

 

[seasick]

After it cools down ( like an hour or so) does it then show charging voltages?

 

[Doc Stressor]

It's odd that you can still start the engine with a low voltage warning. Sounds like an intermittent connection problem. Have you checked the voltage at the battery terminals with a VOM? It sounds like it is actually OK if you can start the engine.

Before you run a diagnostic on your alternator, check the battery ground connection at the ground stud, which is usually mounted on the inside of the transom. It should be a black wire.

 

[seasick]

I am a bit unsure about the reason why the motors restart but to do so, the battery has to be relatively fully charged. I don't know where the 12V reading is coming from but the number is low and is causing the alarm to be raised. It seems the batteries are initially being charged but after a bit the charging stops. Of course everything will still run but the batteries will start to discharge. At some pint the low voltage alarm occurs. I would assume that if you continued to run, the batteries would eventually run down to a more discharged state and you would not be able to restart the motor.

 

[lyncha00]

I think you are right, the motor restarts because the battery still has enough charge, if I were to press on withe the low voltage warnings I believe the battery would simply run down.

Haven't seen this ground stud yet, it must be a bit hidden, will follow neg cables.

 

[lyncha00]

Looking at wiring chart in manual, I can't see any ground other than the green fuel ground, does that mean the ground is on the engine?

 

[seasick]

I don't think the problem is as simple as a bad ground. I am thinking more along the lines of a stator and/or rectifier issue. As I asked earlier, if the motor cools of, what is the voltage after you start it?
If it is normal but after a time, drops to 12 ish, it sure looks related to something failing after heating up.

 

[SkunkBoat]

Could be something on the House thats drawing too much and pulling it down. bad or jammed pump/switch
Try turning off the House breaker and see if error clears.

 

[seasick]

Could be something on the House thats drawing too much and pulling it down. bad or jammed pump/switch
Try turning off the House breaker and see if error clears.

Even if the draw was excessive, the regulator would still put out charging voltage levels. In addition, the motors probably would start right up after the alarm if run down.

 

[SkunkBoat]

Even if the draw was excessive, the regulator would still put out charging voltage levels. In addition, the motors probably would start right up after the alarm if run down.

I disagree. But in any case, to troubleshoot, I would turn of the house to isolate the problem from there. Then I would know for sure that it is not something there.
I would also look at the bilge pumps since they are not connected thru the House breaker. On other boats I have seen jammed bilge pumps NOT blow a fuse but just drag the 12v down.

It appears from his description that the batteries remain charged, at least well enough to start motors. That implies that either the stator/regulator is not working properly(possibly when it heats up) or something is loading the 12v circuit to give the low voltage alarm on the Yamaha gauge. I assume he would also get low volt alarms on his gps/ff and vhf.
It could be anywhere on the 12v circuit on the motor or in the boat. And it could be a poor connection the ground side of the circuit.


I have had 12v problems on my 265. I had a combination of things all at once. The stator had one open winding so it was only putting out 2/3 of what it should. That caused batteries not to charge and one was shot. There was also a really green connection of the house feed on the back of the house breaker that you could not see.

I don't think an F350 has the same stator/regulator setup as an OX66 but you get the point.

Another way to isolate the problem is to run the starter cables of the motor directly to one good battery with no connection to the switches and house. I would do that if I wasn't getting anywhere by staring at things. That will tell you something.

 

[lyncha00]

Well I took it to my marina and they could see the low voltage code which they cleared but couldn't replicate the issue. I ran it today for over an hour (split between batt 1&2) and had 14 volts the whole time. Back to square 1.

I am going to keep my meter with me and, if it happens again, check battery directly to verify gauge is correct. Not sure what else to do.

Bilge pumps have been checked and only electronic being used is a Garmin 5212 so very little draw outside of motor and trim tabs.